The first-born kids in a family do better in school than their siblings who follow, perhaps in part because they face more intense monitoring and rules, a new study finds. Parents tend to limit TV watching, for example, and monitor homework more with “earlier-born children” than with those that follow, the researchers found.

The study published by the National Bureau of Economic Research looked at children born in 1979 (mining data from a national survey) and raised in “intact” families. You can read a “non-technical” summary and the very detailed, and technical, full report here.

In short, the study concluded that moms perceived their first born as doing better in school — and that those children scored higher on academic achievement tests.

Part of that seems to be because the moms had more rules for first-born (or earlier-born if they have more than two) children and reported being more likely to issue consequences if those children performed poorly in school, wrote researchers V. Joseph Hotz of Duke University and Juan Pantano of Washington University in St. Louis.

“We provide robust empirical evidence that school performance of children . . . declines with birth order as does the stringency of their parents’ disciplinary restrictions. And, when asked how they will respond if a child brought home bad grades, parents state that they would be less likely to punish their later-born children,” the authors wrote.

I can hear plenty of parents arguing that isn’t true in their house, and I can imagine plenty of second-born kids (my daughter among them) arguing they do well in school, too, thanks very much.

But I also know there are plenty of times that I am just less intense with kid No. 2 than I was with my first. That can definitely be good — but maybe not always.